Study

Changing grass height alters foraging site selection by wintering farmland birds

  • Published source details Whittingham M.J. & Devereux C.L. (2008) Changing grass height alters foraging site selection by wintering farmland birds. Basic and Applied Ecology, 9, 779-788.

Actions

This study is summarised as evidence for the following.

Action Category

Reduce grazing intensity

Action Link
Bird Conservation

Reduce grazing intensity on grassland (including seasonal removal of livestock)

Action Link
Farmland Conservation
  1. Reduce grazing intensity

    A randomised, replicated trial of different winter cutting regimes, designed to simulate grazing intensity on grasslands in Oxfordshire, England (Whittingham & Devereus 2008), found that different groups of birds prefer different treatments. Foraging song thrushes Turdus philomenus and common starlings Sturnus vulgaris, crows and Eurasian kestrels Falco tinnunculus preferred mown (grazed) plots to unmown (ungrazed) plots. Grey herons Ardea cinerea and meadow pipits Anthus pratensis preferred unmown plots to plots that were mown once or twice. For gamebirds, wood pigeons and hedgerow species, there was no significant difference in numbers between the different mowing regimes.  Seventeen grass fields (average size 5 ha) were used in the experiment, with two treatments (mown once vs. unmown) or  four treatments (unmown, mown once at two different times or mown twice) in each. Winter mowing simulates the effects of grazing or cutting for silage. Grass height did not differ between the 14 replicate plots mown once in November/December, once in January or twice during winter, so one winter cut or grazing period was sufficient to create the habitat advantage for bird groups that prefer short grass.

     

  2. Reduce grazing intensity on grassland (including seasonal removal of livestock)

    A randomized, replicated trial of different winter cutting regimes, designed to simulate grazing intensity on grasslands in Oxfordshire, England (Whittingham & Devereux 2008) found that different groups of birds prefer different treatments. Foraging song thrushes Turdus philomenus, common starlings Sturnus vulgaris, crows (Corvidae) and common kestrels Falco tinnunculus preferred mown (grazed) plots to unmown (ungrazed) plots. Grey heron Ardea cinerea and meadow pipit Anthus pratensis preferred unmown (ungrazed) plots to plots that were mown (grazed) once or twice. For gamebirds, wood pigeon Columba palumbus and hedgerow species, there was no significant difference in numbers between the different mowing regimes. Seventeen grass fields (average size 5 ha) were used in the experiment, with two treatments (mown once vs unmown) or all four treatments in each. Winter mowing was used to simulate the effects of grazing or cutting for silage. Grass height did not differ between the 14 replicate plots mown once in November/December, once in January or twice during winter, so one winter cut or grazing period was sufficient to create the habitat advantage for bird groups that prefer short grass.

     

Output references
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